Arnica rydbergii

Greene

Pittonia 4: 36. 1899

Common names: Rydberg’s arnica
Treatment appears in FNA Volume 21. Treatment on page 371. Mentioned on page 367.
Plants 8–35 cm. Stems (branches from rhizomes) simple. Leaves 2–4 pairs (basal often persistent on sterile rosettes), mostly cauline; petiolate (at least basal) or sessile; blades oblanceolate to spatulate, 2–7 × 0.5–2.5 cm, margins usually entire, sometimes denticulate, rarely dentate, apices usually acute, sometimes obtuse, faces sparsely puberulent, moderately pubescent distally, stipitate-glandular. Heads 1–3(–5). Involucres turbinate-campanulate. Phyllaries 9–15, linear-oblong to narrowly lanceolate. Ray florets 6–10; corollas yellow. Disc florets: corollas yellow; anthers yellow. Cypselae brown, 4–7 mm, densely hirsute (not stipitate-glandular); pappi white, bristles barbellate. 2n = 38, 76.

Phenology: Flowering Jul–Aug.
Habitat: Dry to mesic, exposed, rocky alpine slopes and ridges or alpine meadows
Elevation: 1200–3400 m

Distribution

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Alta., B.C., Colo., Idaho, Mont., Oreg., Utah, Wash., Wyo.

Discussion

References

None.

Lower Taxa

No lower taxa listed.